There are some rare instances when one has to anchor deep but I can never see any reason to anchor deeper than the tidal range plus a metre.
All deep anchoring does is wears out your batteries or arms whichever is the last system of retrieval. Unless of course you have a 10lb anchor, three metres of chain and the rest of the rode is rope. Then the weight of getting it all back on board is easy.
Everyone would like to anchor as shallow as possible, but in many parts of the world there is deep water close to shore.
I am anchored at the moment in 10m of water, but I am only 70m from shore.
My draft is 2m, but there is no way I could safely drop my anchor in 3m.